Monoclinic and hexagonal LaPO4：5 mol.%Eu3＋ phosphors were synthesized with merely adjusting pH values of solutions by a hydrothermal method at the same synthesis temperature. The microstructure, morphology and photoluminescence of Eu3＋-doped LaPO4, which were influenced by different preparation conditions, were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FT-IR）, Raman spectroscopy and luminescence spectroscopy, respec-tively. The specimen showed monoclinic structure in strong acid solution, however, it changed into hexagonal structure in weak acid solution and strong alkali solution. The monoclinic LaPO4：Eu3＋ showed the longest length to diameter ratio, which was attributed to the preferential growth of[-112]. The monoclinic specimen exhibited a slight red shift in infrared spectra, Raman band positions and charge transfer （CT） compared with hexagonal specimens. Moreover, the calculated results of grain sizes, lattice parameters, full width at half maximum in Raman patterns and emission integral intensity were in good agreement with analysis results. The mono-clinic specimen showed the maximal absolute luminescence quantum yield （0.4） and the second lifetimeτ2 （0.52 ms）, which was ac-cordant with red-orange emission in CIE. The5D0→7F1 occupied a dominate position in hexagonal specimens, which indicated that more Eu3＋ in the hexagonal structure were occupied inversion center of symmetry sites.
通过静态浸泡腐蚀实验,采用扫描电子显微镜、X射线能谱仪、电化学实验等研究镁合金铈转化膜在0.05mol/L Na Cl溶液中的腐蚀行为,探讨膜层腐蚀机理。结果表明:随着浸泡时间的延长,膜层发生腐蚀和遭到破坏的程度也随之增强,浸泡初级腐蚀产物组织疏松,腐蚀后期腐蚀产物的致密性和紧实度增加;腐蚀产物主要由镁、氧等元素组成。随浸泡时间的延长,膜层电阻和腐蚀电位先增大后减小,腐蚀电流密度呈现先减小后增大的趋势。
